Which of the following statements about chromosomes is correct? MCQ with Answer and Explanation

Explanation:
Actin (thin) and myosin (thick) filaments slide past each other during contraction, powered by ATP. Collagen is structural, hemoglobin transports oxygen.

Explanation:
Anabaena azollae lives in cavities of the water fern Azolla and fixes atmospheric nitrogen. It is used as a biofertilizer in rice paddies.

Explanation:
The pancreas is a mixed gland: exocrine acini secrete digestive enzymes (trypsin, lipase, amylase) into the duodenum, while endocrine islets secrete insulin and glucagon into the blood. The liver produces bile, not digestive enzymes. Spleen filters blood, gall bladder stores bile.